ANH Motorised stunt Saber experiments (& blades) Part 1

[Mouse Vader]

Will you be adding the light-reflecting tape to the ‘blade’?

Yes I will.

Once I have cores that will spin golf club shafts, balsa dowel AND beach dowel I will make up at least one graflex hilt & a Vader hilt, then I will make wooden blades of balsa And beach (straight round, tapered round & square) painted black & covered in scotchlite fabric. These will be compared for visual likeness to the photo's & film footage we have. They will then be tested for robustness (to distruction) & performance to see what characteristics & foibles they have including how the fabic behaves & what they sound like. These test are the real point of doing all this to try & get the best possible idea of what was going on.

Jon Bunkers recollections (post #16) have almost set this to rest as far as I'm concerned but I will see this through as 'confirmation'. I'm currently making modifications to the Mk2 (with bigger 370 motor & swapable bearings) & both battery packs & trying to sort out how to taper the balsa & beech dowel in a 'quick manner'. Given Peter Diamonds comments (& Prowse) that they broke a lot of blades this may be the big problem with this design. So far spinning untapered 1m beech dowel in the MK1b is only possible with the twin bearing set up, it slows markedly on one bearing in the horizontal. Jon Bunker's sketch has only the one. I'll post more once stuff is done.

 

[Mouse Vader]

Got both cores back on line. Here's the MK1b with the twin bearing, 310 motor running about 590rpm, stuffer driveshaft & struggling with full length beach dowel (somewhat warped). OK until I start to swing it then it starts stalling (listen). I also tried the MK1b with it's single bearing driveshaft with v.sim results.

Here's the Mk2, single bearing, 370 motor about the same rpm, same dowel. You can hear a small amount of slow down on swinging sometimes but is largely OK.

This dowel weighs app. 160gm compared to the 77gm of the golf stick. CoG is about 4" further forward too & combined with the warp is a significant increase in stress on the motor & shows the 370 is also noticeably more powerful.

I originally superglued the dowel stud in place but the vibration & weight of blade caused the dowel to start walking off stud. Had to epoxy it in.

In doing these tests I made a very interesting discovery but I'll need to make a gif from a source video to show what's going on. Basically it confirms the use of a heavy (& warped) blade. Try & get that done soon.

 

[Mouse Vader]

Some quick notes before I get on with this gif.

The JGA25-370 motor was sold as 6V & 646rpm. It is actually delivering 600rpm at 6V (which I know should please someone) and gives app. 100rpm / V over 5 - 7.5V that I tested. There are other motors I've found also listed as JGA25-370 6V 620rpm & variations name eg.GA25-370. I'll be sticking with the known version. Remember I'm getting original rpm as 576.
The gearbox is identical with the JGA25-310 400rpm motor inc. ratio , the motor part is about 15mm longer than the 310 at 35mm.
Jon Bunker gave the Marklin motor he used as app. 50mm & thought the gear ratio was about 20:1 - this would give significantly more torque than I'm getting with the 370 so would certainly handle hardwood dowel even if geared the same as I have, which I think maybe true as I'll go into next post.

 

[Mouse Vader]

So, some time ago in another thread (or 2?) I mentioned I'd seen something odd in a BTS Cantina clip & would go into it later. (VC5 on The ANH LightSaber Blade Reference Thread )

Well it turns out much later.

What I'm now certain of is that OB1's saber isn't running but the blade can be seen to 'freewheel' twice.
Seen in this first gif - watch the black stripe. It 'drifts' across, left to right, then stops at the right hand edge then drifts back right to left. Clearly this can't happen under power . Alec has just taken the swipe to cut off guys arm so there is momentum to provide impetus (& you can hear the clack as he hits). [red dot is start of loop, blue is end]

It does it again as he lowers the blade back down, the stripe goes left to right. Note that it does so at the same speed as he is moving his hand.

This is not strobing as it would advance in the same direction all the time. The motor is not running - there are no wires visible. I know some of you will say you can hear the motor in that clip but I refere you to the following video which has this cantina clip from 4.10. Compare the sound with a clip earlier in the video from 1.48 in which the same sound is audible but not a saber in sight. This maybe the camera or something else but it's the same sound so can't be the saber motor.

One reason I've not brought this up sooner is that I couldn't figure out how the blade freewheels like this. The geared motors I'm using start & stop smartly & show no signs of doing this, at least not until you add a heavy & warped beech dowel. When I came to change the blade over from the MK1b to the MK2 I had my answer. This is the MK1b single bearing, watch the collar grub screw.

The blade is sufficiently heavy & sufficiently warped from the driveshaft axis of rotation for gravity to provide a pendulum action, just as we see happen in the above Cantina scene.

As with nearly all this stuff 100% certain it will never be but we have 3 primary sources saying wooden blades, one of which says balsa and hardwood together with vibration problems & now experimental evidence showing warped hardwood matching original footage. Does it for me.

 

[Mouse Vader]

Made some specific test vid's, both on the MK2 core.

This is a 310 motor & 4.4:1 gearbox (aka 900) & is the easiest to make move. (Under power this combo shows some slow down on holding horizontally & stalls easily on swing. Unpowered in this clip.)

This is the 370 motor & 9.68:1 gearbox, the 'stiffest' combo, but still easy enough to move.

Remember the gif's in last post are slow-mo so compare these clips with the full speed video.

 

[Mouse Vader]

In the interest of completeness & risk of over egging the pudding here is an equally warped balsa dowel for comparison. This is in the MK1b with stuffer driveshaft, twin bearing. The beech dowel rotates easily in this set up. It's rather difficult to get the balsa dowel to move. I've tried getting the same thing to happen with the golf shaft but it won't budge.

Next up is modifying the MK2 bearing set up to be known as MK2b. This incorporates the bearing set up I was going to have as the MK3 as well as being interchangeable with a similar setup to the MK2, so means there will be no MK3.

 

[OdiWan72]

I am speechless...this is "fangineering" at its finest!!!!!

Still interested in a full setup, just in case you´ll consider doing a small run eventually

 

[thd9791]

Excellent! Really good observation, now I can't unsee that wobble. I totally get how that would happen, things being on a bearing system, warped and not turned on. Thank god for that seam-line in the reflective tape

 

[Mouse Vader]

Still interested in a full setup, just in case you´ll consider doing a small run eventually

Noted.

Managed to re-machine the MK2 Tuesday. Went really well & now have the MK2b or possibly the 'Universal core' as I can now run any set up I can think of, inc. the Bunker Blade through Bearing (BBB) with 16mm dowel.

I'll make a spacer for the blue 16x27x7 ball race for the main tests as Jon's sketch shows only one. I've used 2 here as they sit perfectly.

Had a quick thrash with both the stuffer & stud type driveshafts with beech dowel, I was able to completely stall the 370 motor with the stud set up if I stopped a hefty swing suddenly. I was also able break the glue bond holding the stud in (again). I could only get low/medium slow down with the same maneuver on the stuffer. Not sure why that is yet.

I was in Wickes DIY this afternoon too (unusual these days) & picked up some white pine for a square blade as well as a 2.4m length of 18mm dowel labled Lt. hardwood. This looks like balsa (& I can just mark it with my thumbnail) but is noticably denser than balsa but not as heavy as beech. I have the feeling this is the Obeche/Obechi mentioned by Buzby (post #212 Is Darth Vader's saber blade painted (ANH) & blade flexing.). Any who it's interesting stuff & the 2nd peice I looked at was reasonably straight so I bought it. Should be able to make a couple of good long Vader blades with it. Can't be exotic either if Wickes is selling it. (£4.56 for 2.4m). I'll post a pick later have to get dinner ready now.

 

[Mouse Vader]

Yet another short vid. Anyone know what make of wood this is?

 

[LadyFerry]

Yet another short vid. Anyone know what make of wood this is?

Beech?

 

[Mouse Vader]

Not Beech different grain structure. Here's a better picture.

Another with beech underneath & nail marks. I can't mark the beech with my nails.

Did the spacer for MK2b as wells as the snub driveshaft for Bunker's BtB set up.

Spent a couple of hrs re-profiling the blade on a little 'V' plane to taper the dowels but to no avail.



I was hoping to spin the dowel with a cordless drill & run the plane up it pressing the dowel onto the plane with my fingers. If I ran the drill fast it wouldn't cut well & if slow just gouged spiral grooves. Tried a small block plane didn't work at all. Tried the block plane with the dowel in the lath but it thrashed about too much to run at a decent speed & at slow speed cut long spirals,

I'll have to rethink. Anyone any ideas for doing this (UK '70's style?).

 

[vadermania]

Beech?

Pinewood?

 

[vadermania]

Not Beech different grain structure. Here's a better picture.

View attachment 1038403


Another with beech underneath & nail marks. I can't mark the beech with my nails.

View attachment 1038404


Did the spacer for MK2b as wells as the snub driveshaft for Bunker's BtB set up.

View attachment 1038405


Spent a couple of hrs re-profiling the blade on a little 'V' plane to taper the dowels but to no avail.

View attachment 1038407

I was hoping to spin the dowel with a cordless drill & run the plane up it pressing the dowel onto the plane with my fingers. If I ran the drill fast it wouldn't cut well & if slow just gouged spiral grooves. Tried a small block plane didn't work at all. Tried the block plane with the dowel in the lath but it thrashed about too much to run at a decent speed & at slow speed cut long spirals,

View attachment 1038408


I'll have to rethink. Anyone any ideas for doing this (UK '70's style?).

Perhaps the production purchased raw tapered wooden sticks from a british billard cue manufacturer?

 

[Mouse Vader]

Pine has prominent growth rings this doesn't. It most looks like balsa but is denser & harder to mark hence I'm thinking Obechi but as I've not knowingly seen that I'm hoping someone will be able to identify this.

Snooker cues would be straight so there would be no wobbling problems. Jon has also said he doesn't remember the use of cues.

 

[Mouse Vader]

Found this site : HobbitHouse Wood ID site

Pretty sure this is Obeche which is (yet again) very convenient as I was wanting to try it out for blades.

 

[Dann]

Are you just trying to turn a taper on a wood dowel?

I'm not sure I follow.

 

[Mouse Vader]

Things have got a bit mixed up with trying to identify what my 'new' doweling is made of.

I'm having difficulty trying to taper the beech dowel, yes. I don't have a wood turning lathe & my engineering one doesn't have the center to center distance to be that helpful. Using it I have to support the dowel with one hand to stop it thrashing about.

Probably easier to sand the taper on the balsa & Obechi as the balsa certain needs a extremely sharp blade to cut it cleanly. What cuts the beech nicely just tears the balsa.

 

[thd9791]

Every once in a while I make harry potter wand props out of found items (kitchen utensil or tool handles that are already lathed into a design) and use hobby dowels for the shaft. I literally wrap sandpaper around it and go to town to taper the dowels, increasing the time I sand the further down I go. That's exhausting, and probably won't center now that I think about it.

might be why there are rumors of planing the taper, might be easier or more manageable way to make it smaller

 

[Mouse Vader]

It's looking increasing likely that planing is how it's done & that takes time. I'm sure hand held powered planers were about then, & they're not that much quicker either. This would limit the amount of straght tapered blades available & explain the use of untapered & warped versions. Increases the likelyhood of tapered square section too as that's quicker than round. So why use round at all ? unless it's bought like that or the tapered ones are Obechi & sanded.
Going round in circles here, oh the irony. Need to try sanding some balsa/obechi.